[infra] Assembles the SDK using GN rather than create_sdk.py

build/toolchain/win/BUILD.gn

Index: build/toolchain/win/BUILD.gn
diff --git a/build/toolchain/win/BUILD.gn b/build/toolchain/win/BUILD.gn
index cf7b4a699d72a30f0453536c9def205172604388..13d7ae2075a26591e9d332167283aae286608f6a 100644
--- a/build/toolchain/win/BUILD.gn
+++ b/build/toolchain/win/BUILD.gn
@@ -165,9 +165,11 @@ template("msvc_toolchain") {
     }
 
     tool("link") {
-      rspfile = "{{output}}.rsp"
+      binary_output =
+          "{{root_out_dir}}/{{target_output_name}}{{output_extension}}"
+      rspfile = "$binary_output.rsp"
 
-      link_command = "$python_path gyp-win-tool link-wrapper $env False link.exe /nologo /OUT:{{output}} /PDB:{{output}}.pdb @$rspfile"
+      link_command = "$python_path gyp-win-tool link-wrapper $env False link.exe /nologo /OUT:$binary_output /PDB:$binary_output.pdb @$rspfile"
 
       # TODO(brettw) support manifests
       #manifest_command = "$python_path gyp-win-tool manifest-wrapper $env mt.exe -nologo -manifest $manifests -out:{{output}}.manifest"
@@ -175,9 +177,10 @@ template("msvc_toolchain") {
       command = link_command
 
       default_output_extension = ".exe"
-      description = "LINK {{output}}"
+      description = "LINK $binary_output"
       outputs = [
-        "{{root_out_dir}}/{{target_output_name}}{{output_extension}}",
+        binary_output,
+        "{{root_out_dir}}/{{target_output_name}}.lib",
       ]
 
       # The use of inputs_newline is to work around a fixed per-line buffer